There are many sensor systems that indicate the location of an intrusion attempt into a secure location or an attempt to steal a secure asset. For example, a door leading to a secure area might be rigged with a tamper switch that automatically relays a signal to a multiplexer and then onward to a de-multiplexer where the location of the intrusion is determined.
There are presently no interior intrusion detection systems that work for spark sensitive rooms such as those at oil refineries and others at power plants. The known systems for these applications include an electronic signal that can ignite the contents of the room, and thus cause an explosion.
Other types of systems include microwave sensors where a microwave transmitter and receiver are aligned and the intrusion attempt causes a break in the reception thereby triggering an alarm. Once again this type of system will not work inside of a spark sensitive room for the aforementioned reasons. These systems are bulky, expensive and highly noticeable.
These system also are tedious for many applications because much cabling is required to transmit signals indicative of an intrusion attempt. For instance, where a manhole system is desired to be protected from intrusion, (such as by terrorists) it would be necessary to install a great deal of cabling throughout the underground system. Further, this cabling is easily corrupted making the entire system suspect to tamper.
If wireless links were to be used, the reliability of the system is constantly in jeopardy because of the inherent unreliable nature of the wireless technology. An illustration of this is the common occurrence that interference from external sources causes disruption to wireless communications. It is noticeable that these antennas sometimes become unreliable during storms. Additionally, much expensive equipment and installation is required for wireless communications.
A manhole system typically carries underground utilities of which can include water drainage, water intake pipes, electrical systems, etc. A manhole cover provides access to such manhole systems for the purpose of repairs and maintenance.
It is a reasonable assumption that terrorists would like to gain access to underground utility systems because of the mass amount of urban destruction that can be attained in compromising such structures. In some cases, manhole covers are welded to their frames in anticipation of a large public event. Entrances may also be monitored by visual surveillance equipment. Each of these methods are costly and laborious.
Thieves often target works of art and other valuable items. There are certain electronic security systems for the protection of works of art, some of which include microwave transmitters and receivers. The microwave systems operate by sending a signal from a transmitter to a receiver. When the signal is interrupted, the system indicates an intrusion attempt.
These systems are expensive and suspect to tampering.